Incandescent lamp mount structure



March 10, 1959 c. w. PEARSON 2,877,375

INCANDESCENT LAMP MOUNT STRUCTURE Filed Oct. 14, 1955 Inventor:

Charles W. Pearson,

by His At, orney United States Patent 2,877,375 lNCANDESCENT LAMP MOUNT STRUCTURE Charles W. Pearson, Euclid, Ohio, assignor to General Electric Company, a corporation of New York Application October 14, 1955, Serial No. 540,395 4 Claims. (Cl. 313-315) My invention relates to electric incandescent lamps generally, and more particularly to the mount, or filament supporting, structure therefor. I

It is well known that the efliciency of a gas filled incandescent lamp is increased by concentrating the fila ment to minimize gas losses. To that end, mean for some time has employed a coiled-coil filament structure wherein the filament is first helically coiled to form a primary helix which is again helically coiled to form a secondary helix. I have demonstrated that further substantial gains are achieved by operating the lamp with the axis of the coiled-coil filament in a vertical position.

By changing the filament from a horizontal to a vertical position the lamp current is decreased and the light output increased. at rated voltage. In addition to increased efiiciency, the life of the lamp is also increased. The decrease in current signifies an increase in filament resistance which, in turn, signifies an increase in filament temperature. -It is thusapparent that the filling gas in the lamp has less cooling effect on a vertically operated filament than on a horizontally operated one. The reason for the increased life is not as clear. However, it is possible that equilibrium tungsten (filament) vapor pressure in the immediate vicinity of a vertically operated filament may be maintained with a lower rate of vaporization from the filament than in the case of a horizontally operated filament because of the presence of vapors which originate from a lower portion of the filament.

By proper slightmodification of the filament proportions the gain may be taken entirely in efficiency'whereby the filament operates at a still, higher temperature and the efliciency is still further increased while. the life remains the same as for the horizontally operated filament. Conversely, the modification may be such as to maintain the same filament temperature and efliciency as for horizontal operation with attendant further increased life.

In order to realize more fully the benefits of vertical operation of the filament, it is desirable to so mount the filament that its axis will be substantially coincident with the longitudinal axis of the bulb. The majority of socket installations is such that this will insure operation of the lamp with its base either uppermost or lowermost and its filament in a vertical position. However, this presents a problem in properly supporting the filament so that it will be correctly located and not be subject to distortion, particularly when subjected to vibration or shock.

Accordingly, it is an object of my invention to provide an effective mount structure for a coiled-coil filament which extends axially of the bulb.

The vertical or axial mounting of the filament necessitates a supporting mount structure wherein one of the longitudinally extending lead-in conductors supporting the filament is longer than the other. When subjected to vibration such a structure is subject to distortion, particularly in the heavier structures used in higher wattage lamps, which results in improper performance including early burnout of the filament. Attempts to solve the 2,877,375 Patented Mar. 10, 1959 problem by providing more rigid lead-in conductors merely aggravates the difiiculty. In accordance with one aspect of. the present invention, 1 provide a mount structure wherein the elongated lead-in conductors are composed of flexible wires, and the filament and respective adjacent ends of the lead-in wires are interconnected by abridge means to form a unit which is free to vibrate without relative displacement of the ends of the lead-in wires and distortion of the filament. Further features and advantages of my invention will appear from the following detailed description of species thereof and from the accompanying drawing.

In the drawing Fig. 1 is a tilted elevation of a lamp having a mount structure comprising our invention, and

Fig. 2 is an elevation -of a mount structure of somewhat modified form.

Referring to Fig. l of the drawing, the lamp comprises a glass bulb 1 having a cylindrical neck portion 2 and a re-entrant glass stem 3 sealed to the end thereof. The bulb 1 contains a filling of inert gas such as argon or nitrogen or mixtures thereof at a substantial pressure of several hundred millimeters. A coiled-coil tungsten filament 4 is supported from lead-inwires 5 and 6 so that its axis is coincident with the longitudinal axis of the bulb 1. The said lead-in wires 5' and 6 have portions thereof sealed in a flattened press portion 7 of the stem 3 and extend outwardly to contacts on the base 8.

The elongated lead-in wires 5 and 6 extend into the interior. of the bulb along opposite sides of its axis and have their inner ends 9 and 10 bent laterally toward the said axis where they are mechanically and electrically joined to the filament by book portions formed therein and clamped to the filament. The lamp may also contain a conventional heat deflecting disc 11 which is sup-' ported from the stem press 7.

As thus far described, the filament and its supporting structure are subject to distortion due to unequal displacement of the long and short lead-in wires 6 and 5, respectively, when subjected to vibration or shock. In accordance with the present invention, such distortion is'obviated by the provision of bridge means mechanically interconnecting the inner ends 9 and 10 of the lead-in wires. As herein illustrated, the bridge means is composed of a pair of angular wires 12 and 13 which are interconnected by an insulating member 14,'preferably a glass button or rod into which the ends of the wires 12 and 13 are fused and embedded. The opposite ends of the wires 12 and.13 are secured, preferably by welding, to the end portions 9 and 10 of the respective lead-in wires 5 and 6. The filament 4 is preferably further supported by a support wi re 15 having one end embedded in the button 14 and its other end coiled about a midportion of the filament. The rigid bridge member 12, 13, 14 ties together the filament 4 and the ends of the lead-in wires 5 and 6 as a unit which is free to flex about the point of emergence of the said wires 5 and 6 from the stem press 7.

The wires 5 and 6 are preferably composed of a springy metal or alloy such as an iron-nickel alloy containing approximately equal proportions of iron and nickel. The bridge wires 12 and 13 and support wire 15 may be made of molybdenum.

The mount structure shown in Fig. 2 is similar to that shown in Fig. 1 and the same reference numerals have been employed to designate corresponding elements. It differs in the provision of a supplementary brace wire 16 which is welded at one end to an intermedate point on the longer lead-in wire 6 and has its other end loosely anchored in a hollow glass arbor 17 projecting from the stem press 7 between the lead-in wires 5 and 6. The brace member 16 serves to prevent permanent distortion of the lead-in wires 5 and 6 in certain instances where they may be stressed beyond their elastic limit. Thus, in some cases it is desirable to employ lead-in wires 5 and 6 of nickel. In those cases, the nickel wires may be annealed and softened at a point adjacent the stem press 7 by the heat attending the operation of forming the press seal 7, and thereby subjected to permanent distortion in the absence of the brace wire 16.

Although I have shown and described certain details of construction of forms of mount structures embodying my invention, it will be apparent to those skilled in the art that those details may be substantially changed or modified and I therefore aim to cover in the appended claims all such changes or modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electric incandescent lamp comprising a sealed bulb having a longitudinal axis and containing a filling of inert gas, a mount structure comprising a coiled-coil filament having its longitudinal axis substantially coincident with the said bulb axis, a pair of elongated flexible leadin wires of different lengths anchored in and extending from a wall of said bulb longitudinally into the interior of the bulb and along opposite sides of its axis to the vicinity of respective ends of said filament and thence laterally toward said bulb axis where they are electrically and mechanically joined to the said respective ends of the filament, and rigid bridge means mechanically but not electrically interconnecting the laterally extending portions of said lead-in wires at points adjacent their joints with the respective ends of the filament whereby said bridge means forms a tie with said lead-in wires thereby forming a unit to resist distortion from vibration or shock.

2. In an electric incandescent lamp comprising a sealed bulb having a longitudinal axis and containing a filling of inert gas, a mount structure comprising a coiled-coil filament having its longitudinal axis substantially coincident with the said bulb axis, a pair of elongated flexible lead-in wires of different lengths anchored in and extending from a wall of said bulb longitudinally into the interior of the bulb and along opposite sides of its axis to the vicinity of respective ends of said filament and thence laterally toward said bulb axis where they are electrically and mechanically joined to the said respective ends of the filament, and rigid bridge means including a U-shaped wire structure with an intermediate insulating member and located in a plane normal to the plane of said lead wires and mechanically but not electrically interconnecting the laterally extending portions of said lead-in wires at points adjacent their joints with the respective ends of the filament, and a supplementary support wire secured at one end to said insulating member and embracing a midportion of the filament at its other end, whereby said bridge means forms a tie with said lead-in wires thereby forming a unit to resist distortion from vibration or shock.

3. In an electric incandescent lamp comprising a sealed bulb having a longitudinal axis and containing a filling of inert gas, a mount structure comprising a coiled-coil filament having its longitudinal axis substantially coincident with the said bulb axis, a pair of elongated flexible lead-in wires of different lengths anchored in and extending from a wall of said bulb longitudinally into the interior of the bulb and along opposite sides of its axis to the vicinity of respective ends of said filament and thence laterally toward said bulb axis where they are electrically and mechanically joined to the said respective ends of the filament, and rigid bridge means mechanically but not electrically interconnecting the laterally extending portions of said lead-in wires at points adjacent their joints with the respective ends of the filament whereby said bridge means forms a tie wtih said lead-in Wires thereby forming a unit to resist distortion from vibration or shock, and a supplementary brace wire secured at one end to a point on the longer of said lead-in wires intermediate its length and having its other end loosely anchored at the said wall of the bulb between the lead-in wires.

4. In an electric incandescent lamp comprising a sealed bulb having a longitudinal axis and containing a filling of inert gas, a mount structure comprising a coiled-coil filament having its longitudinal axis substantially coincident with the said bulb axis, a pair of elongatedfiexible lead-in wires of difierent lengths anchored in and extending from a wall of said bulb longitudinally into the interior of the bulb and along opposite sides of its axis to the vicinity of respective ends of said filament and thence laterally toward said bulb axis where they are electrically and mechanically joined to the said respective ends of the filament, and rigid bridge means mechanically but not electrically interconnecting the laterally extending portions of said lead-in wires at points adjacent their joints with the respective ends of the filament whereby said bridge means forms a tie with said lead-in wires thereby forming a unit to resist distortion from vibration or shock, and a supplementary brace wire secured at one end to a point on the longer of said lead-in wires intermediate its length and having its other end loosely anchored in a hollow arbor projecting from the said wall of the bulb between the lead-in wires.

References Cited in the file of this patent UNITED STATES PATENTS 1,247,068 Benbow Nov. 20, 1917 2,116,384 Cartun May 3, 1938 2,158,561 Biggs May 16, 1939 2,179,437 Socolofsky Nov. 7, 1939 2,181,295 Biggs et al, Nov. 28, 1939 

